Method and system for combining a conversion between time-division multiplexed digital signals and packetized digital signals with a switching system interface

ABSTRACT

The present invention is a switching system interface providing conversion between time-division multiplexed digital signals and packetized digital signals used to bypass a common control and switch matrix of a class 5 digital switch. The switching system interface includes a network interface for terminating a digital transmission facility that is part of a network architecture. In addition, the interface includes a line/trunk interface, compatible with the internal signals used to operate the line/trunk interface of the class 5 digital switching system and a switch, connected to the network interface and to the line/trunk interface, for routing data between network interfaces and line/trunk interface. The interface also converts the data between time-division multiplexed digital signals and packetized digital signals.

RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 10/971,821 by David M. Smith entitled “METHOD AND SYSTEM FORCOMBINING AN EMERGENCY STANDALONE SWITCHING DEVICE WITH A SWITCHINGSYSTEM INTERFACE,” filed Oct. 22, 2004 now U.S. Pat. No. 7,319,747 whichclaims the priority of U.S. Pat. No. 6,807,273 by David M. Smithentitled “METHOD AND APPARATUS FOR BYPASSING THE COMMON CONTROL ANDSWITCH MATRIX OF A DIGITAL SWITCHING SYSTEM FOR TELECOMMUNICATIONSNETWORKS,” filed Nov. 30, 2001 and are hereby both incorporated in theirentirety by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to telecommunications. Specifically, the presentinvention relates to a system and method of providing a conversionbetween time-division multiplexed digital signals and packetized digitalsignals with a switching system interface utilized to bypass a commoncontrol and switch matrix of a digital switch.

2. Description of the Related Art

A class 5 central office comprises a building or room which houses aclass 5 switching system, which operates to connect telephones and otherdevices used by end-user customers (“subscribers”) to atelecommunications network such as the public switched telephone network(“PSTN”). A class 5 digital switch also converts the analog signals usedby telephones, modems, FAX machines, and some PBX trunks, into thedigital signals that are routed through a digital telecommunicationsnetwork. The class 5 digital switch also provides special services forcaller ID displays and message waiting lights for subscribers, and itprocesses and routes calls from digital PBX trunks, ISDN lines, anddigital loop carriers (“DLC”) to a telecommunications network.

U.S. Pat. No. 6,807,273 (“'273”) discloses a novel method and system forbypassing a common control and switch matrix of a class 5 digital switchby a switching system interface that couples one or more line/trunkframes of the digital switch to one or more transmission facilities in acommunications network that preferably operates under anindustry-recognized protocol.

A common control and switch matrix of a first class 5 digital switch maybe bypassed by a switching system interface that couples one or moreline/trunk frames of the digital switch to one or more industry standarddigital transmission facilities that make up the remote end of anindustry standard DLC architecture. This configuration provides thebenefit that the line/trunk frames associated with the first digitalswitch may be operated by a second class 5 digital switch or mediagateway of any manufacture, so that the legacy software of the firstdigital switch may be discarded and/or any limitations of the legacyswitch matrix may be overcome, while retaining the installed legacyline/trunk frames and cable plant and incurring minimal changes to theinstalled physical plant.

There is a trend to employ networks that carry both voice calls and dataover common transport based on connectionless access protocols such asasynchronous transfer mode (“ATM”) and transport controlprotocol/internet protocol (“TCP/IP”). These networks are also referredto as “packet networks”. Packet networks simplify the problem ofcarrying both voice and data from region to region. Routing calls oversuch a network permits the use of common routing hardware controlled byso-called “soft switches”, which essentially are computers running callprocessing software.

“Media gateways” are specialized packet switches that also convert thetime-division multiplexed digital format of voice calls on trunks fromlegacy class 5 switches into the packetized formats used in packetnetworks. Present methods require the use of a media gateway in order toroute calls from legacy time-division multiplexed equipment through apacket network.

Virtually all media gateways support GR303 as a protocol for interfacingto time-division multiplexed equipment. Therefore, a switching systeminterface for bypassing the common control and switch matrix of a class5 digital switch, by coupling the line/trunk frames of the digitalswitch to digital transmission facilities that make up the remote end ofan industry standard DLC architecture, can be used with a media gatewayto route calls between the line/trunk frames and a packet network.However, the cost and complexity are increased by virtue of the factthat two types of network equipment must be purchased, installed, andadministered. The complexity of this configuration may be furtherincreased if the softswitch that processes calls for the packet networkcontrols both the media gateway and switching system interface.

Therefore, what is needed is a system and method to provide theconversion between time-division multiplexed digital signals andpacketized digital signals within the switching system interface inorder to eliminate separate and different types of costly equipment,such as media gateways.

If a network operator chooses to bypass the common control and switchmatrix of several class 5 digital switches, one or more of theline/trunk frames of each of the digital switches may be placed underthe control of another digital switch that provides call processing fora larger geographical region, in order to reduce the number of switchesin the network. The telecommunications industry often refers to this as“network flattening” or “network collapsing,” and it can provide manyadvantages to the network operator, such as lower equipment costs, loweroperating and maintenance costs, more efficient use of complex switchingsoftware and routing databases, simpler network management, etc.

U.S. application Ser. No. 10/971,821 discloses the use of an emergencystandalone switching device. The switching system interface may then beequipped with the emergency standalone switching device, so that thecombination can be used with the regional full-featured switching systemwhile maintaining the capability to make local and 911 calls in aserving area that is temporarily isolated from the regional system dueto equipment failure, facility damage, or other reasons. Thiscombination also has the advantage that the switching system interfacecan be used to aggregate subscribers in the serving area that are servedthrough DLCs, as well as those served through legacy line/trunk frames.This allows all subscribers served by time-division multiplexedequipment to be protected by the emergency standalone switching devicein the switching system interface, and for call processing to take placethrough one call control interface to the switching system interface.This simplifies the network topology and simplifies the task ofadministering the databases necessary for the emergency standaloneswitching device.

It would also be advantageous to aggregate subscribers who usepacket-based telephones, such as IP phones that are now being used bysome businesses, or who use telephones connected to packet-based accessnetworks, such as new-generation telephone service over cable systems.This would allow all subscribers in a serving area to be protected bythe emergency standalone switching device in the switching systeminterface, and for all call processing to take place through one callcontrol interface to the switching system interface. This configurationprovides the benefit of simplifying the network topology to the pointwhere all forms of telephony would integrate seamlessly into onenetwork.

Therefore, a system and method is needed to implement the conversionbetween time-division multiplexed digital signals and packetized digitalsignals within the switching system interface, along with the emergencystandalone switching device, in such a way that all subscribers in aserving area can be served by the same call processing interface and thesame regional full-featured switching system, and be protected by acommon emergency standalone switching device with a common database. Inaddition, the entire combination should be able to route and processcalls between subscribers within a serving area without the need forexternal switching equipment, such as a softswitch.

Thus, it would be a distinct advantage to provide a system and method tocombine a conversion between time-division multiplexed digital signalsand packetized digital signals with a switching system interface used tobypass the common control and switch matrix of a class 5 digital switch,and also with a switching system interface that includes an emergencystandalone switching device. It is an object of the present invention toprovide such a system and method.

SUMMARY OF THE INVENTION

It is a primary object of this invention to combine a conversion betweentime-division multiplexed digital signals and packetized digital signalswith a switching system interface used to bypass the common control andswitch matrix of a legacy class 5 digital switch, so that thecombination can be used to convert and route calls between time-divisionmultiplexed equipment, such as legacy line/trunk frames, DLCs, and apacket network.

It is a further object of this invention to combine an emergencystandalone switching device that can route calls between subscribers ina serving area without the use of external switching equipment, andregardless of whether the subscribers are served by time-divisionmultiplexed equipment or by any form of pack-based equipment or accessnetwork.

In accordance with the present invention, a conversion betweentime-division multiplexed digital signals and packetized digital signalswith a switching system interface used to bypass the common control andswitch matrix of a legacy class 5 digital switch is provided such thatcalls may be routed between time-division multiplexed equipment and apacket network, and that an emergency standalone switching device mayroute calls between subscribers within a serving area without the use ofexternal switching equipment.

In one aspect, the present invention is a switching system converterproviding conversion between time-division multiplexed digital signalsand packetized digital signals used to bypass a common control andswitch matrix of a class 5 digital switch. The switching systemconverter includes at least one network interface for terminating adigital transmission facility that is part of a packet-networkarchitecture. In addition, the interface includes at least oneline/trunk interface, compatible with the internal signals used tooperate the line/trunk frame of the class 5 digital switching system anda switching means, connected to the network interface and to theline/trunk interface, for routing data between network interfaces andline/trunk interface. The interface may also convert the data betweentime-division multiplexed digital signals and packetized digitalsignals.

In another aspect, the present invention is a method of combiningpacketized digital signals and time-division multiplexed digital signalswith a switching system interface used to bypass the common control andswitch matrix of a legacy class 5 digital switch. The method begins byaccessing a first connection providing internal signals used to controlline and trunk interfaces of the first digital switching system andconvey data in and out of the line and trunk interfaces. Next, aswitching system interface, which is compatible with the firstconnection providing internal signals, is applied to the firstconnection. The switching system interface bypasses at least a portionof the common control and switch matrix. The interface is compatiblewith a digital transmission facility within the telecommunicationsnetwork. The signals are then converted between packetized digitalsignals and time-division multiplexed digital signals through theswitching system interface as required.

In still another aspect, the present invention is an emergency switchingsystem with a switching system interface providing conversion betweentime-division multiplexed digital signals and packetized digital signalsused to bypass a common control and switch matrix of a class 5 digitalswitch. The emergency switching system includes an emergency standaloneswitch for controlling call control functions and means for routing acall from a first subscriber line to a second subscriber line throughthe emergency standalone switch. The emergency switching system may alsoinclude a conversion of time-division multiplexed digital signals andpacketized digital signals. The emergency switching system providesemergency or local call service to a localized area serviced by thedigital switch.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary embodiment of a switching systeminterface that couples the line/trunk frames of a legacy class 5 digitalswitch and DS1s serving DLCs to a host switch using a DLC protocol;

FIG. 2 illustrates an exemplary embodiment of the internal PCM datapaths of the switching system interface of FIG. 1;

FIG. 3 illustrates a switching system interface having additionalfunctions of connecting to IP-based networks and converting betweentime-division multiplexed and packet-based digital signals in thepreferred embodiment of the present invention;

FIG. 4 is a flow chart outlining the steps for converting time-divisionsmultiplexed digital signals to packetized digital signals with aswitching system interface used to bypass the common control and switchmatrix of a legacy class 5 digital switch according to the teachings ofthe present invention;

FIG. 5 is a flow chart outlining the steps for converting packetizeddigital signals to time-division multiplexed digital signals with aswitching system interface used to bypass the common control and switchmatrix of a legacy class 5 digital switch according to the teachings ofthe present invention; and

FIG. 6 illustrates a switching system interface providing a registry andproxy server to enable IP-based call control in an alternate embodimentof the present invention.

DESCRIPTION OF THE INVENTION

A system and method of providing a conversion between time-divisionmultiplexed digital signals and packetized digital signals with aswitching system interface utilized to bypass a common control andswitch matrix of a digital switch is disclosed. FIG. 1 illustrates anexemplary embodiment of a switching system interface that couples theline/trunk frames of a legacy class 5 digital switch and DS1s servingDLCs to a host switch using a DLC protocol. One or more line/trunkinterfaces 105 couple to legacy line/trunk frames via one or moreconnections 104. One or more DS1 interfaces 102 connect to one or moretransmission facilities 101 that operate remote DLC equipment. Inaddition, one or more DS1 interfaces 109 connect to one or moretransmission facilities 110 that connect, in turn, to a host digitalswitch or a media gateway. A time-slot interchange function 107 connectsto the line trunk interfaces 105 and DS1 interfaces 102 and 109 viainternal Pulse Code Modulation (PCM) buses 108, 103, and 106, in orderto make connections between timeslots in the interfaces. Calls are thusrouted through the switching system interface.

FIG. 2 illustrates an exemplary embodiment of the internal PCM datapaths of the switching system interface of FIG. 1. One or moreline/trunk frame interfaces 201 received PCM timeslots originating fromthe legacy line/trunk frames. These PCM timeslots are transmitted overpreset timeslots on PCM busses 204. In a similar manner, PCM timeslotsoriginating from transmission facilities connected to DLCs or to thehost switch are received by DS1 interfaces 202 and transmitted overpresent timeslots on PCM bus 204.

The timeslot interchange function 203 receives time-division multiplexedPCM data from one or more PCM busses 204. The time interchange function203 rearranges the data into new timeslots as necessary and transmitsthe PCM data onto one or more PCM busses 207. The line/trunk interfaces201 then receive the PCM data from preset timeslots on PCM buses 207 andtransmits the PCM data to the legacy line/trunk frames. In addition, DS1interfaces 202 receive PCM data from preset timeslots on PCM buses 207and transmit the PCM data to DLCs and the host switch through externaltransmission facilities.

FIG. 3 illustrates a switching system interface having additionalfunctions of connecting to IP-based networks and converting betweentime-division multiplexed and packet-based digital signals in thepreferred embodiment of the present invention. The original switchingsystem interface includes line trunk interfaces 301, DS1s 302, atimeslot interchange function 303, a PCM bus 304, and a PCM bus 307. Inaddition, the present invention also includes an IP section whichincludes an interface card 310, an IP switch 311, a packet transport 317and a second packet transport 318. Additionally, in the preferredembodiment, the present invention includes a format converter (FC) 312,a packet transport 315 and a packet transport 316. The FC may convertthe time division multiplexed digital voice signals to a packetizedformat and also may optionally compress the voice format (preferablyutilizing a voice compression algorithm such as G.729). The FC may be adigital signal processor (DSP).

Referring to FIG. 3, the format converter 312 receives time-divisionmultiplexed PCM data from preset timeslots on the PCM bus 307. The FCtransmits time-division multiplexed PCM data to preset timeslots on PCMbus 304. The FC 312 also may have IP addresses for receiving packetsfrom the IP switch 311 over the packet transport 316 and fortransmitting packets back to the IP switch 311 over the packet transport315. The packet transports may be implemented as 100baseT, which mayinclude separate transmit and receive connections for each device on thenetwork.

One or more network interface cards 310 may allow IP addresses externalto the switching system interface depicted in FIG. 3 to the IP switch311 over the packet transport 317 and to receive packets over the packettransport 318.

To establish a call from a conventional subscriber telephone to the IPnetwork, analog signals from the telephone are converted into PCM databy hardware in the line frames of the switch and, in turn, interfacewith the line/trunk interfaces 301. The PCM data is then transmitted ona timeslot on the PCM bus 305 to the timeslot interchange 303. Thetimeslot interchange 303 transmits the PCM data onto a timeslot on thePCM bus 307 that is preset for the format converter 312. The FC thenconverts the PCM data to a packet format and transmits the PCM data toan external IP address over the packet transport 318 and the networkinterface card 310. The interface card 310 may then connect to anexternal IP network or any other network. Packets from the external IPaddress are sent to an address in the format converter 312 via theinternal network 310, the packet transport 317, the IP switch 311, andthe packet transport 316. Packets are then converted by the formatconverter 312 into time-division multiplexed PCM data and transmitted ona preset timeslot on the PCM bus 313 to the timeslot interchange 303,which, in turn, transmits the PCM data onto a timeslot on the PCM bus307 that is preset for the conventional telephone connected to theline/trunk frame 301.

The network interface cards 310 and the IP switch 311 may also routepackets between two external IP addresses, which could correspond to twolocal IP telephones or to a local IP telephone and a distant one servedby the network. The switching system interface depicted in FIG. 3 mayutilize the FC to convert the proprietary representation of legacy linestates, such as “on-hook” and “off-hook” into messages that are sent toan external controlling device. In addition, messages may be receivedand interpreted from an external controlling device to apply legacy linesupervision, such as ring voltage. Thus, the external controlling devicemay utilize the legacy telephone lines for making and receiving-phonecalls over a packet network. The device may provide a capability formaking and receiving telephonic calls over a packet network where callsare set up, routed, and torn down over a local area network (LAN) or theInternet. Additionally, the device may include the capability toregister an identity, an address, or other characteristic of thenetwork-based device with the switching system interface. The externalcontrolling device may be used in the PSTN call model to control androute calls and maintain billing information or any other informationassociated with a subscriber. Additionally, the present invention mayinclude generation of call progress tones, such as “dial tone,” “busy,”etc. to be applied to legacy lines under the control from messagesoriginated from an external controlling device. The interface mayinclude the capability for collecting DTMF tones or dial pulses from thelegacy lines, interpreting these tones or pulses as digits, and sendingthe digital information as messages to the external controlling device.The external controlling device may be a pure softswitch that controlscalls without directed access to the PCM data.

FIG. 4 is a flow chart outlining the steps for converting time-divisionmultiplexed digital signals to packetized digital signals with aswitching system interface used to bypass the common control and switchmatrix of a legacy class 5 digital switch according to the teachings ofthe present invention. With reference to FIGS. 3 and 4, the steps of themethod will now be explained. In step 400, analog signals from atelephone are converted into PCM data by line frames of the switch whichinterface with the line/trunk interfaces 301. In step 402, the PCM datais transmitted on a timeslot on the PCM bus 305 to the timeslotinterchange 303. Next, in step 404, the timeslot interchange 303transmits the PCM data onto a timeslot on the PCM bus 307, which ispreset for the format converter 312. In step 406, the PCM bus 307 sendsthe PCM data to the format converter 312. The method then moves to step408 where the format converter 312 converts the PCM data to packet formand transmits the data to an external IP address over the packettransport 318 and the network interface card 310.

FIG. 5 is a flow chart outlining the steps for converting packetizeddigital signals to time-division multiplexed digital signals with aswitching system interface used to bypass the common control and switchmatrix of a legacy class 5 digital switch according to the teachings ofthe present invention. With reference to FIGS. 3 and 5, the steps of themethod will now be explained. The method begins with step 500 where thepackets from the external IP address are sent to an address in theformat converter 312 via the network interface card 310, the packettransport 317, the IP switch 311, and the packet transport 316. Next, instep 502, the packets are then converted by the format converter 312into time-division multiplexed PCM data. In step 504, the time-divisionmultiplexed PCM data is transmitted onto a preset timeslot on the PCMbus 313 to the timeslot interchange 303. In step 506, the PCM data isthen transmitted onto a timeslot on the PCM bus 307 that is preset forthe conventional telephone connected to the line/trunk frame 301.

FIG. 6 illustrates a switching system interface providing a registry andproxy server to enable IP-based call control in an alternate embodimentof the present invention. The switching system interface includes linetrunk interfaces 601, DS1s 602, a timeslot interchange function 603, aPCM bus 604, and a PCM bus 607. In addition, the present invention alsoincludes an IP section which includes an interface card 610, an IPswitch 611, a packet transport 617 and a second packet transport 618.Additionally, in this alternate embodiment, the present inventionincludes a format converter (FC) 612, a packet transport 615 and apacket transport 616. In a similar manner as described in FIG. 3, the FCmay convert the time division multiplexed digital voice signals to apacketized format and also may optionally compress the voice format(preferably utilizing a voice compression algorithm such as G.729). Inaddition, in this alternate embodiment, the present invention mayinclude a processor 620, a packet transport 621 and a packet transport622 communicating with the IP switch 611.

Still referring to FIG. 6, the format converter 612 receivestime-division multiplexed PCM data from preset timeslots on the PCM bus607. The FC transmits time-division multiplexed PCM data to presettimeslots on the PCM bus 604. The FC 612 also may have IP addresses forreceiving packets from the IP switch 611 over the packet transport 616and for transmitting packets back to the IP switch 611 over the packettransport 615. The packet transports may be implemented as 100baseT,which may include separate transmit and receive connections for eachdevice on the network.

One or more network interface cards 610 may allow IP addresses externalto the switching system interface depicted in FIG. 6 to the IP switch611 over the packet transport 617 and to receive packets over the packettransport 618.

To establish a call from a conventional subscriber telephone to the IPnetwork, analog signals from the telephone are converted into PCM databy hardware in the line frames of the switch and, in turn, interfacewith the line/trunk interfaces 601. The PCM data is then transmitted ona timeslot on the PCM bus 605 to the timeslot interchange 603. Thetimeslot interchange 603 transmits the PCM data onto a timeslot on thePCM bus 607 that is preset for the format converter 612. The FC thenconverts the PCM data to a packet format and transmits the PCM data toan external IP address over the packet transport 618 and the networkinterface card 610. The interface card 610 may then connect to anexternal IP network or any other network. Packets from the external IPaddress are sent to an address in the format converter 612 via theinternal network 610, the packet transport 617, the IP switch 611, andthe packet transport 616. Packets are then converted by the formatconverter 612 into time-division multiplexed PCM data and transmitted ona preset timeslot on the PCM bus 613 to the timeslot interchange 603,which, in turn, transmits the PCM data onto a timeslot on the PCM bus607 that is preset for the conventional telephone connected to theline/trunk frame 601.

The network interface cards 610 and the IP switch 611 may also routepackets between two external IP addresses, which could correspond to twolocal IP telephones or to a local IP telephone and a distant one servedby the network. Thus, the present invention shown in FIG. 6 enablescalls to be set up, routed and torn down over a LAN or the Internetwithout the need for an external controlling device, such as asoftswitch or a proxy server. Additionally, the present invention mayfurther include the processor 620 to register conventional subscriberphones that are connected to the legacy line frames and proxy server.The processor 620 provides control of call states for these phones. Inthe embodiment depicted in FIG. 6, the present invention serves as anetwork end-point for an IP-based call control method, such as SessionInitiation Protocol, thereby eliminating the need for a softswitch. Theregistration may include the network-based device identity, networkaddress and other characteristics with the switching system interface.The processor may also enable one or more network-based proxy servers toregister their identities, network addresses, and other characteristicsof each legacy line or phone device associated with the switching systeminterface, thereby creating a public network.

The present invention may also be used to convert time-divisionmultiplexed digital signals and packetized digital signals in a networkutilizing an emergency standalone switching device. The emergencystandalone switching device may be used to route calls betweensubscribers in a serving area without the use of external switchingequipment and regardless of whether the subscribers are served bytime-division multiplexed equipment or by any form of pack-basedequipment or access network.

The present invention provides the combination of a conversion functionbetween time-division multiplexed digital signals and packetized digitalsignals with as switching system interface used to bypass the commoncontrol and switch matrix of a legacy class 5 digital switch, so thatthe combination can be used to route calls between time-divisionmultiplexed equipment, such as legacy line/trunk frames and DLCs and apacket network. The present invention provides the interoperabilitybetween different types of digital signals in an economical fashion.

While the present invention is described herein with reference toillustrative embodiments for particular applications, it should beunderstood that the invention is not limited thereto. Those havingordinary skill in the art and access to the teachings provided hereinwill recognize additional modifications, applications, and embodimentswithin the scope thereof and additional fields in which the presentinvention would be of significant utility.

Thus, the present invention has been described herein with reference toa particular embodiment for a particular application. Those havingordinary skill in the art and access to the present teachings willrecognize additional modifications, applications and embodiments withinthe scope thereof.

It is therefore intended by the appended claims to cover any and allsuch applications, modifications and embodiments within the scope of thepresent invention.

1. A switching system converter providing conversion betweentime-division multiplexed digital signals and packetized digital signalsused to bypass a common control and switch matrix of a class 5 digitalswitch, the switching system converter comprising: a switching systeminterface having means for bypassing a common control and switch matrixof a class 5 digital switch, the switching system interface having: atleast one network interface for terminating a digital transmissionfacility that is part of a network architecture; at least one line/trunkinterface, compatible with internal signals used to operate theline/trunk interface of the class 5 digital switching system; and aswitching means, connected to the network interface and to theline/trunk interface, for routing data between the network interfacesand the line/trunk interface; and means for converting data betweentime-division multiplexed digital signals of a legacy line frame of alegacy line and packetized digital signals utilizing pulse codemodulation (PCM) data transport.
 2. The switching system converter ofclaim 1 wherein the packetized PCM data transport is Internet Protocol(IP).
 3. The switching system converter of claim 1 further comprising:means for converting a proprietary representation of a legacy line stateof the legacy line into a message sent to an external controllingdevice; and means for receiving and interpreting the message from theexternal controlling device to apply legacy line supervision; wherebythe external controlling device provides a capability for making andreceiving telephonic calls over a packet network.
 4. The switchingsystem converter of claim 3 further comprising: means for generatingcall progress aural tones applied to the legacy line under the controlof a message from the external controlling device; means for collectingDTMF tones or dial pulses from the legacy line; means for interpretingthe tones or pulses as digits; and means for sending the digitalinformation as a message to the external controlling device; whereby theexternal controlling device controls calls without direct access to thePCM data.
 5. The switching system converter of claim 1 furthercomprising: means for converting a proprietary representation of alegacy line state of the legacy line into a message sent to a packetnetwork-based device; and means for receiving and interpreting themessage from the packet network-based device to apply legacy linesupervision, the packet network-based device providing a capability formaking and receiving telephonic calls over a packet network wherebycalls are set up, routed, and torn down over a local area network (LAN)or the Internet.
 6. The switching system converter of claim 5 furthercomprising a registry means allowing a network-based device to registeran identity, an address or other characteristic of the network-baseddevice with the switching system interface.
 7. A switching systeminterface providing conversion between time-division multiplexed digitalsignals and packetized digital signals used to bypass a common controland switch matrix of a class 5 digital switch, the switching systeminterface comprising: a switching system interface having means forbypassing a common control and switch matrix of a class 5 digitalswitch: at least one network interface for terminating a digitaltransmission facility that is part of a packet-network architecture; atleast one line/trunk interface, compatible with internal signals used tooperate a line/trunk frame of the class 5 digital switching system; aswitching means, connected to the network interface and to theline/trunk interface, for routing data between the network interfacesand the line/trunk interface; and means for converting data betweentime-division multiplexed digital signals and packetized digitalsignals.
 8. The switching system interface of claim 7 wherein the meansfor converting data between time-division multiplexed digital signalsand packetized digital signals includes utilizing a digital signalprocessor.
 9. The switching system interface of claim 7 furthercomprising: one or more digital signal processing means, connected tothe switching means, for capturing telephone numbers dialed bysubscribers connected to the line/trunk interface; a memory for storinga list of telephone numbers; a means for comparing the capturedtelephone numbers against the stored list of telephone numbers; one ormore data-oriented network interfaces connected to the switching means;whereby the switching system interface will identify dial-up internetcalls placed by the subscribers to known internet service providers anddivert the dial-up internet calls to the data-oriented networkinterfaces and prevent the dial-up internet calls from reaching theterminal of the network architecture and the terminal is relieved of thedial-up internet calls.
 10. A method of combining time-divisionmultiplexed digital signals and packetized digital signals with aswitching system interface used to bypass the common control and switchmatrix of a legacy class 5 digital switch, the method comprising thesteps of: utilizing a switching system interface to bypass a commoncontrol and switch matrix of the digital class 5 switch; accessinginternal signals of the class 5 digital switching system used to controlline and trunk interfaces of the class 5 digital switching system andconvey data in and out of the line and trunk interfaces; providing aswitching system interface comprising at least one network interfaceconnected to at least one digital transmission facility that is part ofa network architecture, and comprising interfaces compatible with theinternal signals; and connecting the compatible interfaces of theswitching system interface to the internal signals of the class 5digital switching system, the connection between the compatibleinterfaces and the internal signals enabling a terminal in the networkarchitecture to directly operate the internal signals to providetelecommunications service to subscribers connected to the line andtrunk interfaces without the use of the common-control-and switch matrixof the class 5 digital switching system; and converting time-divisionmultiplexed digital signals to packetized digital signals through theswitching system interface.
 11. The method of combining time-divisionmultiplexed digital signals and packetized digital signals of claim 10further comprising the steps of: identifying dial-up internet callsdialed by subscribers connected to the line and trunk interfaces; anddiverting identified dial-up internet calls to a facility for handlinginternet traffic separate from the terminal.
 12. The method of combiningtime-division multiplexed digital signals and packetized digital signalsof claim 11 wherein the step of identifying dial-up internet callsincludes: providing a means within the switching system interface forcapturing telephone numbers dialed by subscribers connected to the lineand trunk interfaces; providing a memory for storing within theswitching system interface a list of telephone numbers of known internetservice providers; and providing a means within the switching systeminterface for comparing the telephone numbers dialed by the subscribersagainst the list in order to identify dial-up internet calls.
 13. Themethod of combining time-division multiplexed digital signals andpacketized digital signals of claim 10 further comprising the steps ofconnecting a digital signal processor within the telecommunicationsnetwork to the second connection to enable the media gateway tocommunicate with the internal signals.
 14. The method of combiningtime-division multiplexed digital signals and packetized digital signalsof claim 10 wherein the step of converting time-division multiplexdigital signals to packetized digital signals includes: receivingsignals originating form a line trunk frame; extracting Pulse CodeModulation (PCM) data and signal information from these signals;transmitting the PCM data on a timeslot; packetizing the PCM data; andtransmitting the packetized data to an external IP address.
 15. Anemergency switching system with a switching system interface providingconversion between time-division multiplexed digital signals andpacketized digital signals used to bypass a common control and switchmatrix of a class 5 digital switch, the emergency switching systemcomprising: a switching system interface used to bypass a common controland switch matrix of a digital switch; an emergency standalone switchfor controlling call control functions, the emergency standalone switchcomputed to the switching system interface; and means for routing a callfrom a first subscriber line to a second subscriber line through theemergency standalone switch; means for converting time-divisionmultiplexed digital signals and packetized digital signals; whereby theemergency switching system provides emergency or local call service to alocalized area previously serviced by the digital switch.
 16. Theemergency switching system of claim 15 further comprising a databasestoring a plurality of directory numbers of subscribers located withinthe localized area, the database providing directory numbers for callcontrol by the emergency standalone switch for providing local oremergency call service to a subscriber serviced by the class 5 digitalswitch.